New theme won’t display categories

Hi, I applied a new theme to my blog (www.azcongresswatch.com) and now the only category that will display is Uncategorized. The snippet I’m using to call the categories is <?php wp_list_cats(); ?>.

– Applying my old theme shows the categories once again, so the database isn’t broken
– If I create a NEW category, it shows up (just created one called “Legislation” and it works
– Just upgraded to 2.0.7, still no luck.

Any help would be appreciated! Thank you!